1. Field of the Invention
One embodiment of the present invention relates to a display device. One embodiment of the present invention also relates to a method of manufacturing the display device.
Note that one embodiment of the present invention is not limited to the above technical field. For example, one embodiment of the present invention relates to an object, a method, or a manufacturing method. One embodiment of the present invention relates to a process, a machine, manufacture, or a composition of matter. One embodiment of the present invention relates to a memory device, a processor, a driving method thereof, or a manufacturing method thereof.
Note that in this specification and the like, a semiconductor device generally means a device that can function by utilizing semiconductor characteristics. Thus, a semiconductor element such as a transistor or a diode and a semiconductor circuit are semiconductor devices. A display device, a light-emitting device, a lighting device, an electro-optical device, an electronic device, and the like may include a semiconductor element or a semiconductor circuit. Therefore, a display device, a light-emitting device, a lighting device, an electro-optical device, an electronic device, and the like include a semiconductor device in some cases.
2. Description of the Related Art
In recent years, research and development have been extensively conducted on liquid crystal elements as a display element used in a display region of a display device. In addition, research and development have been extensively conducted on light-emitting elements utilizing electroluminescence (EL). As a basic structure of these light-emitting elements, a layer containing a light-emitting substance is provided between a pair of electrodes. Voltage is applied to this light-emitting element to obtain light emission from the light-emitting substance.
Light-emitting elements are a self-luminous element; thus, a display device using the light-emitting elements has, in particular, advantages such as high visibility, no necessity of a backlight, and low power consumption. The display device using the light-emitting elements also has advantages in that it can be manufactured to be thin and lightweight and has high response speed.
A display device including the display elements can have flexibility; therefore, the use of a flexible substrate for the display device has been proposed.
As a method of manufacturing a display device using a flexible substrate, a technique has been developed in which a semiconductor element such as a thin film transistor is manufactured over a substrate such as a glass substrate or a quartz substrate, for example, the semiconductor element is fixed to another substrate (e.g., a flexible substrate) by using an organic resin, and then the semiconductor element is transferred from the glass substrate or the quartz substrate to the other substrate (Patent Document 1).
In some cases, over a light-emitting element that has been formed over a flexible substrate, another flexible substrate is provided in order to protect a surface of the light-emitting element or prevent entry of moisture or impurities from the outside.
Display devices are expected to be applied to a variety of uses and become diversified. For example, a smartphone and a tablet terminal with a touch panel are being developed as portable information terminals.